You'll find the recipe - actually several - on the Container Gardening forum, but the following link will take you directly to the best discourse available on container soils. It's worth reading through many of the other posts on that forum as well, both for help on locating or substituting ingredients and tips for the most efficient means of fertilization. Container gardening is vastly different from inground gardening and the same methods/products do not work equally well for both.

Here is a link that might be useful: Container soils - all you need to know

Thank you so much for pointing me in a more understandable direction before I move near a ton of mass.

Only starting the thread and am thankful I did ot go forward with a disaster tomorrow.

Little concerned that this might not be appropriate to growing vegetables

It doesn't matter what type of plants you are growing - the principles of container gardening remain the same. You can adjust various mixes to more suit different plants. As an example, the 'gritty mix' referred to the previous link is best suited to long term containers......such as those that might be used for growing blueberries or other woody shrubs and small trees. It is also excellent for most houseplants.

And remember that organic gardening principles and methods are not necessarily limited only to edible plants :-) We can/should try to follow them with any kind of gardening activity.

What is your concern?

You are essentially growing in a large container, rather than a raised bed. I say this because the difference is determined by soil hydrology - how water behaves. Partially bury a 1 quart container and you have a mini raised bed. Isolate your (what one would be tempted to call a) raised bed from the wicking effects of the earth, and you have a large container.

You're largest issue is that no matter what you decide to use as the basis for your soil, if it's predominantly organic, it's going to break down into particles so fine you'll have issues with excess water retention in years subsequent to the first 2-3. If you plant anything perennial in your containers, it sort of complicates the issue, unless you're willing to lift & transplant any perennials on a regular basis. The organic fraction of the soil will gas out and need 'topping off' on a yearly basis, and that takes care of the shrinkage issue, but doesn't address future drainage issues, which is where your focus should be.

Many would suggest you use compost and add sand for 'drainage', but that won't work because the sand + increasingly fine particles will quickly cause the bottom 6" (or more) of the container to turn soupy and anaerobic. My first impression would be that you need a soil based on a large fraction of large (BB-size) inorganic material like pumice/perlite/vermiculite amended with things like finished compost and pine bark fines; but it might also be possible to employ some sort of wicking mechanism to remove excess water if you'd like to explore that idea. With no knowledge pf how your container is constructed, it's difficult to do anything other than toss it out as a potential topic or fix.

Al

At the moment it is a 30 cubic foot empty box on stilts.

I plan to line it with course rock to a drain, but now see that is unnecessary because of hydrology. I guess I did not pay to much attention in fluid mechanics, just enough to get buy I am a EE and at the time was more interested in getting to an afternoon bridge game.

I was going to install a Goodyear liner into the box to keep chemicals from leaching in from building materials.

So I have a clean slate, given the proper material I can install wicks up through the drain. I am guessing from what I have read I would need two that would come up through the drain and run through the meridian.

The question is at what depth should they run the length of the container and how much of the 7 feet.

Just thinking out loud but could a moisture sensor then be attached to the wick to determine when watering was necessary?

I am also thinking that it might be more practical to us 5 gal buckets and 30 Gal storage containers and top with moss for aesthetics.
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I think deciding on what you'll use as the growing medium should come before deciding how to drain it.

How woulds you feel about a slight design modification that leaves you with a flange mounted above the liner with a tail-piece attached that goes through the liner & hangs several inches below the bottom of the planter? You could use the tailpiece as your wick and probably remove most of the perched water from the soil, allowing you to use a mix of pine bark + something like Turface or calcined DE and perlite as other fractions of the soil. If you engineered any 'fall' on the planter bed, it would be easy to locate the lowest spot. You could also use 2 drains in opposite corners, connected in the middle. Your biggest challenge would simply be how to camoflage the plumbing.

What are we planting? fleurs or veggies? anything cascading?

Al

I was going to install course rock tapered to the center drain and then laying the liner on top of that. Because of the drainage issue I inferred that was not really needed as much as wicking. I am totally open to proper engineering, and was going to let the tail hang. Is there minimum maximum to the tail. Because we engineered for 2 tons there are 6 inches joices for plenty of support. I am also starting to grok that a "wick" is not necessarily a wicking material such as cloth or wool, but a mechanical structure to lower the mechanical depth of container and thus can be metal or medical PVC if there is such a thing.

When you state two drains connected in middle, You mean the wick is connected in middle and then run out to the two drains.?

I want to do veggies, especially since I think we will see near doubling inflation if only for the cost of trucking.

I will be using 5 gal pails off the arbor for upside down tomatoes and source of squash, cukes maybe some melons on arbor that will have lattice support.

At the moment it is a 30 cubic foot empty box on stilts.

I plan to line it with course rock to a drain, but now see that is unnecessary because of hydrology. I guess I did not pay to much attention in fluid mechanics, just enough to get buy I am a EE and at the time was more interested in getting to an afternoon bridge game.

I was going to install a Goodyear liner into the box to keep chemicals from leaching in from building materials.

So I have a clean slate, given the proper material I can install wicks up through the drain. I am guessing from what I have read I would need two that would come up through the drain and run through the meridian.

The question is at what depth should they run the length of the container and how much of the 7 feet.

Just thinking out loud but could a moisture sensor then be attached to the wick to determine when watering was necessary?

I am also thinking that it might be more practical to us 5 gal buckets and 30 Gal storage containers and top with moss for aesthetics.
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You picked up on the wick concept quickly. If you use a flange with a removable tailpiece, you can fill the tailpiece with soil or fine sand. If you can taper the bottom toward the hole in the flange, the fine material will serve as the deepest part of the container and increase the gravitational flow potential of all the water in the container proper. The result is any perched water will move into what it 'thinks' is the deepest part of the container, but which will in fact be the tailpiece. Any perched water should then be contained in only the tailpiece & not the medium proper. I can see you understand the concept, so I can leave the details safely in your hands - unless you have questions?

Al

Nice box.

So the new questions are, with wick mode
At what depth should the wicks run at X inches
Wicking through the main drain for how many Y inches.

I think I grok your tailpipe?
The question here are how many inches would the tailpipe be?
At what depth should the top of the tail pipe be in the box?
Should wicks run through the tailpipe or is sand sufficient to lower the ground level?

I am guessing that the pipe lowers the ground so the trick is to find where the perched water level is and make the pipe longer than that. So in this case with a 18 inch depth 6 - 9 inch tail would be sufficient.

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A quick google search came up with this...

http://easygrowvegetables.com/html/wickingbed.html

http://www.instructables.com/id/Wicking-Beds/

http://green-change.com/2009/05/01/wicking-beds-water-efficient-gardening/

Here is a link that might be useful: Wicking Bed technology

So the new questions are, with wick mode
At what depth should the wicks run at X inches
Wicking through the main drain for how many Y inches.
I think I grok your tailpipe?
The question here are how many inches would the tailpipe be?
At what depth should the top of the tail pipe be in the box?
Should wicks run through the tailpipe or is sand sufficient to lower the ground level?

I am guessing that the pipe lowers the ground so the trick is to find where the perched water level is and make the pipe longer than that. So in this case with a 18 inch depth 6 - 9 inch tail would be sufficient.

Only one flange/tailpipe would be required if you can isolate its position as the lowest point of the container by building in some taper to that point. Ideally, the top of the flange would be flush with the top of your membrane and fastened to the container bed. No wicks into the media proper would be required. I envision a flange as the lowest point in the box and a removable tailpiece about 8" long secured to the flange through the bed. The tailpiece would have a cap on the bottom with a hole in it and screen covering the hole. You will need to figure out a way to keep the fine sand or Turface screenings from escaping through the drain hole. If you want to do some further engineering with an elbow & some flex tubing to divert the water so it's not just dripping out of the tailpiece & blowing all over everything below, that's fine.

As you know, you want the material in the tailpiece to have greater capillary attraction than the actual media for best efficiency. If you include Turface as a significant fraction of your soil, you'll enhance its ability to hold water w/o impacting aeration significantly, and reduce shrinkage due to gassing out proportionate to the volume of Turface and other stable aggregates used. If you screen some or all of the Turface over insect screen, you can use the fines as the wick material in the tailpiece.

It looks like you understand everything well & just need to implement.

Al

I am not to worried about what is below the planter since that is another bed of shrubs. Though I guess it would be practical to route over to one of the support posts.

As for the fine particulate, Your elbow suggestion made me think "why not steal from plumbing and use a common drain trap". This way there is no special screening required for keeping the medium in the pipe other than gravity.

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(I'm not that much of a geek)

Mechanically I think this is sound and it can be made of stainless material so there is no issue of chemical leaching. The question is now on thickness of pipe, is there a time limit to evacuate the water from container which would require a thicker tail pipe.

For 5 gal container wicking, does the wick remain on bottom of pail or does it have to be suspended in the medium. As an electrical engineer I would speculate that the capillary action is the same as current flow the wick is the wire and the medium is the resistance. Moisture is thus the electron connectivity so as long as the moisture connects the perched layer to the wick you have drainage flow. Thus for tailpipe or wick, all that is need is contact with medium to allow for drainage flow.

Next is the upside down plantings. I would then surmise that the plant itself is now the wick. and one 5 gal container could support a large plant on bottom and several small volume veggies on sides and top?

I'd skip the trap because you're overly complicating things for no gain - and you run the risk of breaking continuity at the top of the second bend. With a straight tailpiece & no screen between the medium and the wick material, continuity is assured.

Any thickness of pipe you choose is fine. I'd say that anything in the 3/4" to 1-1/2" range would be fine. I'd probably use 1-1/4 or 1-1/2 pipe.

It's true that for tailpipe or wick, all that is need is contact with medium to allow for drainage flow.

The 5 gallon hanging plantings are like strawberry pots. I like soils like the gritty mix that are coarse enough that they supply little or no perched water; even then. I would wick them to be on the safe side. I'd hang them by the handle & drill 4 holes in the bottom - two to drain freely & two with a continuous wick in one & out the opposite hole. Screwing a baffle into the bucket walls above the holes you create for inserting the plants will help change the soil's angle of repose and help to keep soil from being flushed out of the holes when you water. Still, you should try to water slowly so water doesn't stack in the soil and get pushed laterally through the planting holes, wetting stems & foliage and possibly introducing soil-born fungaluglies.

Al

Looking for an osmotic membrane on the internet is a bust, all are filters.

You had mentioned orange bags. I have plenty of them.

Would affixing a screen to the bottom of the tail piece and overlapping many layers of the orange bag work or will the sand migrate with the water seepage over time.

I thought I had a bag with fine holes but I recycled it.

The other thought was simply using weed barrier fabric but I would think i am back to the issue of being able to significantly purge water from summer downpours

Use 2" genova then, or 3" if you like - or more than one drain .......

In the lower part of the tailpiece from the bottom up, I think I would start with a screen over the drain holes, then maybe a couple of inches of some large particulates like crushed granite or Haydite with a wick pulled through the center and through another screen, then I would fill the rest with the Turface fines.

You could also utilize two or more drains, one w/wicking material, the others w/o. This would very quickly drain the soil of all water above the normal PWT height because it's GFP would simply squeeze it out of the soil. All drains could be T'd to the same common drain line. You would then only be depending on your single wicking tailpiece to remove any water that would normally perch in the media

Al

So this "Closed Wicking bed" can save up to 50% of all water & it is said that a good mulch can save up to 25-35% of water on a plant bed. Then the two should save at least 70% of the water used.
They did not cover materials that can hold 4-10 times their own weight. This could be mixed in the back fill of OM.
Coir is one example.

Next
I was toying with the idea of lining the box sides and bottom with waterbed heaters for winter greenhouse. Insulated foam / heater/ liner. I figured I could set the thermostats in the soil for lowest setting maybe 50 degrees. then encase the arbor with a heavy mil plastic. Hoping to grow cold weather crops.

You'll want two layers of greenhouse film for dead air and a vent with an auto vent opener for that setup, one layer of film should have good light diffusion. There are already soil heating cables for that purpose and you'll want to calculate a comparative consumption and heat output (not cheap) and analyze with the ambient temp - a sheathing insulation at R-3 in the air will do for most nights in that zone. Shouldn't need anything but bottom heat if adequately insulated.

That setup should be nothing to make a 1" SCH40 PVC frame with a vent for cool weather crops, maybe inserting into pipes installed at corners and middle, maybe a couple screws to overengineer to ensure wind doesn't carry away....

And I'll read a good Al thread any day.

Dan